1. Field of the Invention
This invention relates, generally, to a marine propulsion unit. More particularly, it relates to a marine propulsion unit having a cylinder driving an impeller, thereby, creating thrust.
2. Background Art
Currently, many vessels including, but not limited to, submarines, recreational, commercial, or military use a bow thruster or a stern thruster assembly having a propeller connected to a gear train and the gear train is connected to a bulky external motor needing a large compartment to house the external motor and heavy drive assembly. Many vessels warrant the need for a bow thruster for safety and ease of operation, but they do not have the space to house the motor and drive assembly within a concealed compartment. For example, smaller single engine boats have limited space and warrant the need for a more compact and lighter weight assembly. Thus, there is a need for a bow thruster that does not have an external motor so that the assembly can easily fit within a vessel.
Prior art submarine propulsion assemblies use an external propeller at the stern of the vessel. These propulsion assemblies require bulky engines and motors that can consist of fuel sources and have complicated transmission systems including, but not limited to, drive shafts and gears. The integration of moving parts creates detectable vibrations and noise. Additionally, these moving parts require maintenance, trouble shooting, and repair. Thus, there is a need to have an electromagnetic propulsion system having only one moving assembly capable of being contained within a submarine. This is more desirable because the propulsion system is more quiet, more reliable, more efficient, and easier to maintain and repair. Further, by having only one moving assembly, the use of an engine or a motor is eliminated and the need for a transmission is eliminated, whereby lowering fuel consumption. Another result is the reduction of equipment casualties and maintenance shutdowns, thereby, improving operational readiness.
Conventional impeller driven vessels drive the impeller via a drive shaft centrally connected to an impeller. The drive shaft is an obstruction of the water flow through the impeller. Also, a spinning drive shaft is susceptible to entanglement of water born debris including, but not limited to, ropes, fishing line, or weeds. Therefore, there is a long felt but unfulfilled need for the impeller being connected to a cylinder, whereby, the cylinder is the rotating portion of a brushless motor.
However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified needs could be fulfilled.